Apparatus for producing artificial silk



Dec. 12, 1933. A. HARTMANN ET AL 1,939,300

\ APPARATUS FOR PRODUCING ARTIFICIAL SILK Filed Oct. 30, 1926 J12 vevzf re M; Ma .l M flaw-wk:

Patented Dec. 12, 193.3

1,939,300 APPARATUS FOR r t g lzucmo ARTIFICIAL August Hartm'annand Gotthard Bauriedel, Barmcn, Germany, as'signors to American Bemberg Corporation, New York, N. Y.

Application October 30,

and in Germany November 2,

2 Claims.

Among. the numerous methods of producing artifical silk from cellulose solutions, the viscose process and the cuprammonium process according to the wet stretch-spinning method are the I only ones which'have finally proved capable of being used technically on a large scale. Whereas however it was possible at an early date in the manufacture of viscose artificial silk to shorten the time and reduce the costs of manufacture by introducing the centrifuge for storing and twisting the filaments the introduction of the spinning centrifuge to simplify the textile part in the manufacture of cuprammonium silk has met with difficulties.

The centrifuge has the advantage that with it it is possible in one operation to obtain a filament which can be wound onto the reel and is twisted in a manner rendering it immediately capable of being used. In the known technical form of the viscose spinning process, the filament is introduced from above into a spinning centrifuge which is rotating at a suitably rapid speed, the filament, owing to centrifugal force,-

being thrown against the wall of the drum while being simultaneously twisted and collected there in crossed layers in the form of a so-called spinning cake.

According to the wet stretch-spinning process the cuprammonium silk is producedin a stretch spinning vessel, called in short a funnel. As is well known a neutral or slightly alkalinebath is used as a rule as a precipitant. The filaments produced in this manner and still containing copper were hitherto collected on reels, rollers, bobbins or the like and acidified with dilute acid, before or on the reel, roller, bobbin or the like.

Attempts have been made to combine the treatment of a cuprammonium cellulose solution to obtain artificial silk according to the wet stretchspinning process with the advantages of the centrifuging process. For this purpose the filaments produced beforehand in the known stretchspinning vessels were introduced in a manner corresponding to the viscose process into the spinning drum. The filaments were then acidified with dilute sulphuric acid in various ways in the spinning drum and finished in a known manner. Other experiments have shown that a satisfactory product can be obtained by acidifying the filament before the centrifuge and that under tension. For this purpose a drawing device is inserted between the acidifying device and the centrifuge which on the one hand leads the filament to the centrifuge and on the other hand 1926, Serial increases the draught of the centrifuge to ensure the necessary tension.

Accordingly the invention consists in a process for manufacturing twisted artificial silk from cuprammonium cellulose solutions in which the filament after leaving the spinning device is acidified under tension and thereafter is drawn in and twisted bya so-called spinning centrifuge.

Since anyacid' adhering to the filament is instantaneously thrown out in the centrifuge the acidifying must be ended before the filament enters the centrifuge. To obtain this result surely according to the invention the path of the filament from the spinning vessel to the centrifuge can be extended. This may be done 7 by suitable arrangement of drawing rollers, for instance by placing the rollers in an elevated position so that the filamentfirstly raises from the acid bath and then descends again to the centrifuge. It is also possible to lead the filament around the drawing'roller and to so elongate the path. a

The drawing or delivery roller or the guide rod may be smooth, ribbed or serrated. They may be made of glass, porcelain, soft or hard rubber and other acid-resisting materials,- the same applying to any guiding rollers.

In order to obtain a filament of a uniform titre it'is necessary that the filament adheres sufiiciently to the drawing device so that it does not slip. For this purpose a sufficient length of contact between the filament and the roller is necessary. This may be obtained by increasing the angle of contact around the roller, by arranging pressure rollers under the action of a weight or spring and so on.

In the drawing in which is illustrated a preferred form of the invention, 1 represents a spinning apparatus having an outlet opening 2 through which the filament 4 leaves, passes under 5 a reversing rod 3 and a guiding roller or the guide rod 5a, both of which dip into a vessel 6 filled with dilute sulphuric acid, up to a positively driven delivery roller 7, from which the filament 4 passes through the so-called spinning tube 9, to the spinning centrifuge 8.

A pressure roller 10 is rotatably mounted on the free end of a lever 11, which is rockable around an axis 12. The roller 10 presses the filament 4 against the positively driven drawing 106 roller 7 by its weight, or if the pressure so produced is not sufhcient, a spring may be arranged which presses the roller 10 against the roller 7.

V The acid vessel 6 may have the form of an inclined gutter upon which fall drops of acidJllO The roller 7 may also be made of special more adhesive material or may be lined with such material. Firstly, a rubber is a suitable material, but also other acid proof adhesive materials may be used, for instance, artificial resin or phenol formaldehyde condensation products or mixtures of these materials with other acid proof materials.

In all constructional forms the guiding roller 5 may in some circumstances be omitted. 1nstead of treating the moving filament with'acid at the reversing rod 3 or on the way from this rod to the delivery roller 7, a satisfactory result is also obtained if the delivery roller 'ljrevolves in dilute acid or if acid is allowedto trickle over it, and it is of advantage if some acid runs back along the filament towards the reversing rod 3.

It is possible to work with one delivery roller alone as guiding device. In this case the filament running onto the delivery roller must be treated with acid or acid allowed to trickle over it.- However it is preferable 'to provide the delivery roller 7 with a filament guide or a reversing rod 3 having a braking action upon the speed at which the -filament is taken 01f, so that the filament is subjected to a definite higher tension between filament guide or reversing rod and delivery roller, and it has been found especially advantageous to acidify the filament at this point and under the tension produced in this way. This tension can be varied by suitably shaping the filament guide or the reversing rod. This tension of the filament may also be increased by inserting suitable guiding or tension rollers. The tension can be increased in this way as des'iredfbut has a definite limit, as the filament may otherwise be damaged by the numerous friction points. v

I What we claim is:

1. In a device for stretch-spinning filaments, in combination, a filament spinning funnel, a guiding means situated therebeneath in such a position that filaments passing thereover will pass through a treating medium, a drawing roller arranged above said guiding means, and a rotatably-mounted roller so situated that pressure is brought to bear on filaments passing over said drawing roller.

2.'In a device of the class set forth, in combination, a filament spinning apparatus and a drawing wheel for stretching the spun filaments, said'drawing wheel being provided with a means to prevent the filaments from slipping thereover, said means including a rotating member in frictional engagement with said drawing wheel.

AUGUST HARTMANN. GOT'I'HARD BAURIEDEL. 

